Are bamboo sleep sacks actually better than cotton?

Verified-purchase reviewers and parenting communities describe bamboo viscose as softer and more temperature-regulating, which parents of hot-sleeping babies tend to prefer. However, at least one r/NewParents thread in the data reports a PurComfy bamboo sack ran too warm for a larger toddler, so the 'cooler' claim isn't universal. Cotton is cheaper, more durable in the wash, and easier to find in multipacks.